Sacroiliac joint (SIJ) pain can cause lower back pain and pelvic discomfort. However, there is no established standard treatment for SIJ pain. Extracorporeal shock wave therapy (ESWT) is a novel, non-invasive therapeutic modality for musculoskeletal disorders. The mechanism underlying shockwave therapy is not fully understood, but the frequency with which ESWT is applied clinically has increased over the years.

Thirty patients with SIJ pain were assigned randomly to ESWT (n＝15) and sham control (n＝15) groups. The ESWT group received 2，000 shockwaves with energy set to the maximum level tolerable by the patient (energy density＝0.09－0.25 mJ/mm²). The probe was oriented perpendicular to the posterior SIJ line, and moved up and down along the joint line. The sham control group received 2，000 shockwaves with the probe oriented parallel to the posterior SIJ line. A 10-cm numeric rating scale (NRS) and the Oswestry Disability Index (ODI) scores were assessed before the intervention, and 1 and 4 weeks post-intervention. Participants were instructed to refrain from using any other conservative treatment, including anti-inflammatory medication and other physical modalities during the study.

In the ESWT group, NRS decreased significantly at post-treatment week 4 [3.64 (95% confidence interval, 2.29－4.99)] compared to baseline [6.42 (5.19－7.66); P<0.05]. ODI improved at 1 and 4 weeks compared to baseline, but not significantly. In the sham group, NRS and ODI did not differ at any post-treatment time point. There was a significant group difference in NRS at week 4 post-treatment [3.64 (2.29－4.99) in the ESWT group vs. 6.18 (5.34－7.02) in the sham control group; P<0.05], but this was not the case for ODI.

ESWT represents a potential therapeutic option for decreasing SIJ pain.